This invention relates to the field of friction clutches, and more particularly to release mechanisms for use with friction clutches for heavy duty vehicles.
Known friction clutches provide a releasable torsional connection between a motor vehicle engine flywheel and an associated transmission. The basic clutch structure includes a clutch cover, a pressure plate, a driven disc and a flywheel. A clutch housing encloses the clutch and connects the engine block with the transmission housing. The clutch cover is fixed to the flywheel which is in turn fixed to the engine crankshaft. The pressure plate is rotatably fixed but axially displaceable with respect to both the flywheel and the cover. The driven disc is rotatably fixed to an input shaft of the transmission by a splined connection. The driven disc is axially trapped between the flywheel and the pressure plate. The driven disc has friction facing elements on opposite sides of a radially outer disc element for engagement with the flywheel and the pressure plate. The pressure plate is axially biased toward the flywheel by one or more clutch springs to compress the driven disc therebetween, causing the driven disc to rotate as a unit with the pressure plate and flywheel in a clutch engaged condition.
A vehicle operator can selectively release the clutch to allow relative rotation between the input shaft and the engine by displacing a floor mounted clutch pedal with their foot. Displacement of the pedal, transmitted through a linkage, effects an axial movement of a clutch release assembly to a clutch released condition. The clutch release assembly engages the radially innermost tips of clutch levers or diaphragm spring fingers. Displacement of the tips of the levers or fingers, achieved by employing the release assembly, relieves the spring load exerted against the pressure plate, thereby releasing the clutch.
Repeated clutch releases and clutch engagements will cause the friction material to wear. With wear, the location of the release assembly in the engaged condition shifts as the pressure plate moves toward the flywheel. The shift in the position of the release assembly, without the presence of an adjusting mechanism, will present itself to the vehicle operator as a lower clutch pedal height. However, the operator will be unaware of how much remaining useful life the clutch has. In automated systems, in which a clutch is being actuated by an automatic mechanism, no evidence of wear will present itself to the vehicle operator until the clutch begins to slip. To quantify the amount of friction element wear, and to accurately assess the need to replace the driven disc for a typical clutch, one must disconnect the clutch housing and transmission from the engine, and remove the clutch cover and pressure plate assembly from the flywheel.
It is desired to provide a mechanism providing an indication of clutch wear and/or of remaining useful clutch life without separating the transmission from the engine.
A clutch fork and clutch housing assembly for use with a motor vehicle clutch includes a clutch housing, a shaft, a fork, a first index mark, and a first washer. The shaft is mounted to the clutch housing and defines an axis of rotation. The fork has a sleeve portion which is disposed over the shaft and is coaxial therewith. The fork has a pair of tines and a lever arm extending from the sleeve portion. The fork is pivotable relative to the clutch housing about the axis of rotation. The first index mark is disposed on the sleeve portion at a first end of the sleeve portion. The first washer is disposed over the shaft and is axially disposed between the first end of the sleeve portion and a corresponding first part of the clutch housing. The first washer is rotatably fixed relative to the clutch housing. An alignment of the first index mark and the second index mark in a clutch-engaged condition indicates one of a worn condition and an unworn condition.
A clutch fork washer for use with a motor vehicle clutch fork has a substantially annular body portion. The washer has a first aperture passing therethrough. The washer also has anti-rotation feature extending axially therefrom, and a plurality of index marks disposed on a side opposite the axially extending anti-rotation feature.
A clutch fork and clutch housing assembly for use with a motor vehicle clutch includes a clutch housing, a shaft, and a fork. The shaft is mounted to the clutch housing and defines an axis of rotation. The fork has a sleeve portion disposed over the shaft and coaxial therewith. The fork also has a pair of tines and a lever arm extending from the sleeve portion. The fork is pivotable relative to the clutch housing about the axis of rotation. The shaft is selectively removable from the housing and the fork from an outside of the clutch housing.
The disclosed clutch provides a mechanism for indicating clutch wear and/or remaining useful clutch life without separating the transmission from the engine.